1. Field of the Invention
The present invention relates to a method for fabricating a polyethersulfone nanofiber membrane with improved mechanical strength for water treatment by electrospinning.
2. Description of the Related Art
The global water shortage crisis has become a serious global problem and the importance of water has become increasingly emphasized. Under these circumstances, the market for separation membranes as essential materials for the water industry is considered a very attractive market with an average growth rate of around 10% per annum and is expected to grow steadily from now on. In line with Korean government's strong policy to promote the water industry and the expanding global market for separation membranes, there has been rapidly growing interest in separation membranes in Korea. Nevertheless, frontier technologies and human resources for the development of separation membranes as essential materials for the water industry and related materials thereof are still unsatisfactory in Korea, thus failing to narrow the gap between Korea and advanced countries.
Fluorinated polymers, particularly, polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE), sulfone polymers, such as polyethersulfone (PES) and polysulfone (PS), and polyolefin materials, such as polyethylene (PE) and polypropylene (PP), are typically used as polymeric materials for separation membranes. However, the conventional materials for water treatment are insufficient in strength and cause membrane fouling during long-term operation. This fouling requires physicochemical washing, which is a cause of a gradual decrease in the operating life of membranes. Further, the physicochemical washing reduces the porosity of membranes, impeding high-flux/low-energy operation of the membranes. In view of the foregoing, there is a need to develop an improved method for producing membrane materials that can overcome the physicochemical drawbacks of conventional materials, dramatically increase the water permeability of membranes, and provide a fundamental solution to the problems of membrane fouling. There is also a need to secure an economical method for fabricating membranes whose performance is enhanced by synthesizing new structures and an economical method for fabricating membranes using new raw materials.
Many approaches to solve the above problems have been proposed. Particularly, technologies associated with the development of materials for water treatment using electrospun nanofibers are considered the most important approaches.
Electrospinning is a technology that has been used to produce ultrafine microfibers using electricity. Electrospinning has the advantage of low investment cost in equipment and enables the production of various kinds of fibers, including low-denier fibers composed of not more than 10 polymer chains per cross-sectional area as well as general spun fibers with higher deniers. However, the application of filters based on electrospinning technology to environmental fields has been mostly focused on atmospheric applications, particularly, air filters for filtering dust and other impurities from air.
As discussed above, despite the recent rapid advances in technologies for fabricating water treatment materials using electrospun nanofibers, information about reliability and application technologies is still insufficient. The technologies are still limited in their application to environmental water treatment due to various reasons such as lack of technical feasibility and insufficient economic evaluation.
Thus, there is an urgent need for research on a method for producing electrospun nanofibers that have great potential as environmental filter materials and improved mechanical strength for water treatment applications.